Authors:

Spencer Frank(University of Central Florida)

Giovanni Barbera(Purdue University)

Bo Cheng(Purdue University)

Xinyan Deng(Purdue University)

The leading edge vortex is key in lift generation on flapping
wings. Its stability depends on the transport of the entrained
vorticity into the wake via spanwise flow. This study
investigates the generation and enhancement of spanwise flow
based on the chordwise vorticity that results from the tilting
of the leading edge vortex and trailing edge vortex. Two
dynamically scaled robotic model wings, one rectangular and one
insect wing shaped based on \textit{Drosophila melanogaster}
(fruit fly), are submerged in a tank of mineral oil and actuated
into flapping motion. The overall flow structure was visualized
and measured by a Volumetric 3-component Velocimetry (V3V) system
(TSI, Inc.). From the three dimensional flow measurements
obtained, the chordwise vorticity resulting from the vortex
tilting is shown. The distribution of the resulting spanwise
flow induced by the vortex tilting is shown using isosurfaces and
on a planar cross section downstream of the leading edge. It is
observed that the largest spanwise flow is located in the area
between the tilted leading edge vortex and the tilted trailing
edge vortex, supporting our hypothesis that the vortex tilting
enhances the spanwise flow. This vortex tilting
mechanisms helps to explain the overall flow structure and the
stability of the leading edge vortex.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.DFD.D6.8